WO2013147149A1 - Procédé de fabrication d'une ébauche de verre pour disque magnétique et procédé de fabrication d'un substrat de verre pour disque magnétique - Google Patents

Procédé de fabrication d'une ébauche de verre pour disque magnétique et procédé de fabrication d'un substrat de verre pour disque magnétique Download PDF

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Publication number
WO2013147149A1
WO2013147149A1 PCT/JP2013/059505 JP2013059505W WO2013147149A1 WO 2013147149 A1 WO2013147149 A1 WO 2013147149A1 JP 2013059505 W JP2013059505 W JP 2013059505W WO 2013147149 A1 WO2013147149 A1 WO 2013147149A1
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WIPO (PCT)
Prior art keywords
cutting
molten glass
glass
press
pair
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PCT/JP2013/059505
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English (en)
Japanese (ja)
Inventor
勝彦 花田
磯野　英樹
秀和 谷野
村上　明
佐藤　崇
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Hoya株式会社
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Publication of WO2013147149A1 publication Critical patent/WO2013147149A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B7/00—Distributors for the molten glass; Means for taking-off charges of molten glass; Producing the gob, e.g. controlling the gob shape, weight or delivery tact
    • C03B7/10—Cutting-off or severing the glass flow with the aid of knives or scissors or non-contacting cutting means, e.g. a gas jet; Construction of the blades used
    • C03B7/12—Cutting-off or severing a free-hanging glass stream, e.g. by the combination of gravity and surface tension forces
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
    • C03B11/06—Construction of plunger or mould
    • C03B11/08—Construction of plunger or mould for making solid articles, e.g. lenses
    • C03B11/088—Flat discs
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B7/00—Distributors for the molten glass; Means for taking-off charges of molten glass; Producing the gob, e.g. controlling the gob shape, weight or delivery tact
    • C03B7/14—Transferring molten glass or gobs to glass blowing or pressing machines
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2215/00—Press-moulding glass
    • C03B2215/70—Horizontal or inclined press axis

Definitions

  • the present invention relates to a method for manufacturing a magnetic disk glass blank and a method for manufacturing a magnetic disk glass substrate.
  • a personal computer, a notebook personal computer, or a DVD (Digital Versatile Disc) recording device has a built-in hard disk device for data recording.
  • a hard disk device used in a portable computer such as a notebook personal computer
  • a magnetic disk in which a magnetic layer is provided on a glass substrate is used, and the magnetic head slightly floats above the surface of the magnetic disk. Magnetic recording information is recorded on or read from the magnetic layer by a (DFH (Dynamic Flying Height) head).
  • a glass substrate is preferably used because it has a property that it is less likely to undergo plastic deformation than a metal substrate or the like.
  • the density of magnetic recording has been increased.
  • the magnetic recording information area is miniaturized by using a perpendicular magnetic recording method in which the magnetization direction in the magnetic layer is perpendicular to the surface of the substrate.
  • the storage capacity of one disk substrate can be increased.
  • the flying distance from the magnetic recording surface of the magnetic head is extremely shortened to reduce the magnetic recording information area.
  • the magnetic layer is formed flat so that the magnetization direction of the magnetic layer is substantially perpendicular to the substrate surface. For this reason, the surface irregularities of the glass substrate are made as small as possible.
  • the surface unevenness of the end surface of the glass substrate is made as small as possible in addition to the main surface of the glass substrate.
  • a glass substrate used for a magnetic disk is manufactured, for example, by the following method. Specifically, in the method, a lump of molten glass (hereinafter referred to as a gob) is supplied onto a lower mold that is a receiving gob forming mold, and the lower mold and an upper gob forming mold are used. A gob is press-molded to produce a plate-like magnetic disk glass blank (hereinafter referred to as a glass blank), and then processed into a glass substrate for an information recording medium (Patent Document 1).
  • a gob a lump of molten glass
  • a glass blank a plate-like magnetic disk glass blank
  • the grinding process for example, grinding using alumina-based loose abrasive grains is performed.
  • the first grinding step and the second grinding step are performed using loose abrasive grains having different particle sizes.
  • the particle size of the loose abrasive used in the second grinding step is set smaller than the particle size of the loose abrasive used in the first grinding step. Thereby, rough grinding and fine grinding are performed in this order.
  • the polishing step includes, for example, a first polishing step using free abrasive grains such as cerium oxide and a hard resin material polisher, and a second polishing step using, for example, colloidal silica and a soft resin material polisher.
  • the grain size of the abrasive grains used in the first polishing process is smaller than the grain size of the abrasive grains used in the second grinding process during the grinding process.
  • the particle size of the abrasive grains used in the second polishing step is smaller than the particle size of the abrasive grains used in the first polishing step.
  • the first grinding step, the second grinding step, the first polishing step, and the second polishing step are performed in this order, and the surface quality such as the surface roughness of the glass substrate is improved. Process to gradually improve.
  • the gob falls freely and the distance from cutting to pressing is relatively long. Therefore, as shown in FIG. It becomes easy to destabilize (in the example shown in the figure, the gob is falling so as to shift to the left instead of directly below).
  • the upper end of the gob is positioned in the driving direction of the lower cutting blade from the lower cutting blade of the pair of cutting blades (left of FIG. 15). Is pushed out. Then, the direction of rotation about an axis extending along a direction perpendicular to the center of the gob G G with respect to the driving direction of the street and the lower cutting blade, the rotation moment occurs in the gob.
  • the gob falls while rotating, and the dropping posture and the dropping trajectory become unstable. In this way, the falling posture and the trajectory of the gob are destabilized, so that the part that first contacts the gob in the press surface of the die during pressing and the mode of stretching of the molten glass during the press are different for each press. Variation occurs.
  • the first contact portion with the gob in the press surface of the die at the time of pressing is the starting point of heat transfer from the gob
  • the first contact portion with the gob in the press surface of the die is different for each press.
  • the temperature distribution in the mold surface varies with each press.
  • This mechanism causes variations in the flatness of individual glass blanks and variations in flatness between individuals. Such variation in flatness within and between individual surfaces affects the setting of the processing amount (allowance) in post-processing (grinding, polishing, etc.).
  • the cutting part (shown in FIG. 15) on the surface of the gob is partially dissipated by heat conduction when it comes into contact with the cutting blade, so that the temperature is lower than other parts on the surface of the gob. It is. For this reason, when the cut part on the surface of the gob comes into contact with the press surface of the die during pressing, the periphery of the cut part on the surface of the gob cools and hardens faster than other parts, so that the glass blank is relatively deep. A sheer mark is generated (for example, 50 to 100 ⁇ m). Thus, when a shear mark is generated in a relatively deep place of the glass blank, it affects the setting of the processing amount (allowance) in post-processing (grinding, polishing, etc.).
  • the flatness of such a glass blank can be improved by grinding (first grinding step), and a shear mark formed at a relatively deep location can be removed.
  • first grinding step a shear mark formed at a relatively deep location
  • the machining allowance (the amount of cutting) in the grinding process is increased.
  • the machining allowance in the grinding process is increased, deep cracks are generated on the surface of the glass blank, so that the machining allowance (polishing amount) is inevitably increased in the polishing process, which is a subsequent process, so that deep cracks do not remain.
  • the vicinity of the outer peripheral edge portion of the main surface of the glass blank is rounded off, and the “sag problem” occurs at the edge portion. That is, since the vicinity of the outer peripheral edge portion of the glass blank is rounded off, when a magnetic disk is produced using this glass blank as a glass substrate, the distance between the magnetic layer near the outer peripheral edge portion and the magnetic head is the glass substrate. It becomes larger than the flying distance of the magnetic head in another part of the head. Further, since the vicinity of the outer peripheral edge portion has a rounded shape, surface irregularities are generated.
  • the recording and reading operations of the magnetic head are not accurate in the magnetic layer near the outer peripheral edge. This is "who's problem”. Further, since the machining allowance in the polishing process becomes large, the polishing process is not practically preferable because it takes a long time.
  • an object of the present invention is to provide a method for producing a glass blank for magnetic disk excellent in flatness in order to efficiently produce a glass substrate for magnetic disk in which surface irregularities on the main surface are suppressed.
  • a first aspect of the present invention is a method for manufacturing a glass blank for a magnetic disk having a pair of main surfaces, comprising a pair of cutting blades arranged opposite to each other in the horizontal direction and shifted from each other in the vertical direction. Cutting the molten glass supplied from the molten glass supply unit in cooperation, dropping the molten glass lump formed by the cutting, and after the cutting step, the molten glass lump is moved to a predetermined press position.
  • a press step of forming a glass blank by press forming with a press surface of a pair of molds, and between the cutting step and the pressing step, the pair of cuts at the time of cutting the molten glass It is characterized in that the dropping of the lump is guided to the press position so as to cancel the rotational moment of the lump of molten glass caused by the extrusion by the blade.
  • a second aspect of the present invention is a method for manufacturing a magnetic disk glass blank having a pair of main surfaces, wherein the pair of cutting blades are arranged so as to face each other in the horizontal direction and are shifted from each other in the vertical direction. Cutting the molten glass supplied from the molten glass supply unit in cooperation, dropping the molten glass lump formed by the cutting, and after the cutting step, the molten glass lump is moved to a predetermined press position.
  • a press step of forming a glass blank by press forming with a press surface of a pair of molds, and between the cutting step and the pressing step, the pair of cuts at the time of cutting the molten glass It is characterized in that the rotation of falling of the lump after cutting is regulated by canceling the rotational moment of the lump of molten glass caused by extrusion by the blade.
  • a third aspect of the present invention is a method of manufacturing a glass blank for a magnetic disk having a pair of main surfaces, wherein the pair of cutting blades are arranged to face each other in the horizontal direction and are shifted from each other in the vertical direction. Cutting the molten glass supplied from the molten glass supply unit in cooperation, dropping the molten glass lump formed by the cutting, and after the cutting step, the molten glass lump is moved to a predetermined press position.
  • Driving speed of the cutting blade disposed above the pair of cutting blades so as to cancel the rotational moment of the molten glass lump caused by the extrusion by the blades ,
  • By expediting than cutting blade disposed on the lower side characterized by restricting the rotation of the fall of the mass after cutting.
  • the molten glass lump that is being cut in the cutting step may be pressed with the pair of dies from both sides in the dropping direction.
  • the lump dropping may be guided by pressing air flowing in a horizontal direction between the cutting step and the pressing step.
  • a method for manufacturing a glass blank for a magnetic disk having a pair of main surfaces wherein the pair of cutting blades are arranged so as to face each other in the horizontal direction and to be shifted from each other in the vertical direction.
  • the molten glass lump that is being cut in the cutting step may be pressed with the pair of dies from both sides in the dropping direction.
  • the molten glass in the cutting step, may be pressed by a pressing member provided in the vicinity of the pair of cutting blades.
  • the pair of cutting blades are an upper cutting blade and a lower cutting blade that are arranged to be shifted from each other in the vertical direction and are arranged to face each other in the horizontal direction, and the lower cutting blade
  • the contact portion of the blade with the molten glass is curved so as to protrude toward the direction away from the upper cutting blade so as to suppress the horizontal displacement of the molten glass, and has a thickness in the vertical direction. It may be configured.
  • the molten glass in the method for manufacturing a glass blank for a magnetic disk, in the cutting step, may be cut in a state where the molten glass is pressed by air flowing in a horizontal direction.
  • the molten glass lump is formed such that a portion of the entire surface of the lump excluding a cutting site and the pair of mold press surfaces are first in contact with each other.
  • the press position is adjusted in advance.
  • the viscosity of the molten glass when flowing out from the molten glass outlet is preferably in the range of 500 dPa ⁇ s to 1050 dPa ⁇ s.
  • a fifth aspect of the present invention is a method for manufacturing a magnetic disk glass substrate, wherein the magnetic disk glass blank manufactured by the above magnetic disk glass blank manufacturing method is used to manufacture a magnetic disk glass substrate. It is characterized by doing.
  • the schematic block diagram which shows an example of the magnetic disc produced using the glass substrate for magnetic discs.
  • a sectional view of a magnetic disk The figure which shows the state in which a magnetic head floats on the surface of a magnetic disc. The figure explaining the surface unevenness
  • disconnection unit in the modification of 1st Embodiment The figure which shows the press molding process of the modification of 1st Embodiment.
  • disconnection unit of 2nd Embodiment. The figure which shows the press molding process of 2nd Embodiment.
  • FIG. 1A is a schematic configuration diagram illustrating an example of a magnetic disk manufactured using a glass substrate for a magnetic disk.
  • FIG. 1B is a schematic cross-sectional view of a magnetic disk.
  • FIG. 1C is a diagram illustrating a state in which the magnetic head floats on the surface of the magnetic disk.
  • the magnetic disk 1 has a ring shape and rotates around a rotation axis.
  • the magnetic disk 1 includes a glass substrate 2 and at least magnetic layers 3A and 3B.
  • an adhesion layer, a soft magnetic layer, a nonmagnetic underlayer, a perpendicular magnetic recording layer, a protective layer, a lubricating layer, and the like are formed.
  • a Cr alloy or the like is used for the adhesion layer.
  • the adhesion layer functions as an adhesive layer with the glass substrate 2.
  • a CoTaZr alloy or the like is used.
  • nonmagnetic underlayer for example, a granular nonmagnetic layer is used.
  • a granular magnetic layer is used for the perpendicular magnetic recording layer.
  • a material made of hydrogen carbon is used for the protective layer.
  • a fluorine-based resin or the like is used for the lubricating layer.
  • the magnetic disk 1 will be described using a more specific example.
  • an in-line type sputtering apparatus is used to form a CrTi adhesion layer, a CoTaZr / Ru / CoTaZr soft magnetic layer, a CoCrSiO 2 nonmagnetic granular underlayer, and CoCrPt—SiO 2 on both main surfaces of the glass substrate 2.
  • a TiO 2 granular magnetic layer and a hydrogenated carbon protective film are sequentially formed. Further, a perfluoropolyether lubricating layer is formed on the formed uppermost layer by dipping.
  • the magnetic disk 1 rotates around the rotation axis at a rotation speed of 7200 rpm, for example.
  • each of the magnetic heads 4 ⁇ / b> A and 4 ⁇ / b> B of the hard disk device floats by a distance H from the surface of the magnetic disk 1 as the magnetic disk 1 rotates at high speed.
  • the distance H at which the magnetic heads 4A and 4B fly is, for example, 5 nm.
  • the magnetic heads 4A and 4B record or read information on the magnetic layer.
  • the magnetic recording information area can be miniaturized and magnetic recording can be performed by performing recording or reading on the magnetic layer at a short distance without sliding with respect to the magnetic disk 1. Achieve high density.
  • the processing of the surface unevenness of the glass substrate 2 includes grinding using fixed abrasive grains having a small machining allowance, and, as a result, first polishing and second polishing capable of reducing the machining allowance. It is made after. Therefore, the conventional “who problem” is solved.
  • the surface unevenness of the main surface of the glass substrate 2 used for such a magnetic disk 1 has a flatness of, for example, 4 ⁇ m or less and a surface roughness of, for example, 0.2 nm or less.
  • the flatness of 4 ⁇ m or less is a target flatness required for a magnetic disk substrate as a final product.
  • Flatness means the flatness specified in JIS B0621. Specifically, it is the surface irregularity of the glass surface, and when the surface of the glass blank is sandwiched between two geometric parallel planes, The distance between two planes when the distance is minimum.
  • the flatness can be measured, for example, using a commercially available flatness tester.
  • the roughness (Ra) of the main surface is an arithmetic average roughness defined in JIS B 0601. Further, the roughness (Ra) of the main surface can be measured by an atomic force microscope and calculated by a method defined in JIS R1683: 2007.
  • FIG. 2 is a diagram for explaining surface irregularities.
  • the surface irregularities can be defined by roughly four irregularities according to the wavelength of the irregularities.
  • the surface unevenness has the largest wavelength undulation (wavelength of about 0.6 ⁇ m to 130 mm), waveness (wavelength of about 0.2 ⁇ m to 2 mm), micro waveness (wavelength of about 0.1 ⁇ m to 1 mm), roughness ( The wavelength is 10 nm or less).
  • the swell can be expressed by using the flatness as an index
  • the roughness can be expressed by using the arithmetic average roughness Ra as an index.
  • Aluminosilicate glass, soda lime glass, borosilicate glass, or the like can be used as the material for the magnetic disk glass substrate in the present embodiment.
  • aluminosilicate glass can be suitably used in that it can be chemically strengthened and a glass substrate for a magnetic disk excellent in the flatness of the main surface and the strength of the substrate can be produced.
  • the aluminosilicate glass has a SiO 2 content of 50 to 75% and Al 2 O 3 in terms of mol% when converted to oxide standards. 1 to 15%, at least one component selected from Li 2 O, Na 2 O and K 2 O in total 12 to 35%, at least one selected from MgO, CaO, SrO, BaO and ZnO And 0 to 20% in total, and at least one component selected from ZrO 2 , TiO 2 , La 2 O 3 , Y 2 O 3 , Ta 2 O 5 , Nb 2 O 5 and HfO 2 It is preferable to use an aluminosilicate glass having a composition of 0 to 10% in total.
  • FIG. 3 is a diagram showing a flow of one embodiment of a method for manufacturing a glass substrate for magnetic disk.
  • a plate-shaped glass blank having a pair of main surfaces is produced by press molding (step S10).
  • the formed glass blank is scribed to produce an annular glass substrate (step S20).
  • shape processing is performed on the scribed glass substrate (step S30).
  • the glass substrate is ground with fixed abrasive grains (step S40).
  • the end surface of the glass substrate is polished (step S50).
  • step S60 1st grinding
  • polishing is performed to the main surface of a glass substrate (step S60).
  • chemical strengthening is performed on the glass substrate after the first polishing (step S70).
  • step S80 is performed on the chemically strengthened glass substrate (step S80).
  • FIG. 4 is a plan view of an apparatus used in the press molding process.
  • the apparatus 101 includes four sets of press units 120, 130, 140, 150 and a cutting unit 160.
  • the cutting unit 160 is provided on the path of the molten glass flowing out (supplied) from the molten glass outlet (supply unit) 111.
  • the molten glass is cut by the cutting unit 160, so that a lump of molten glass (hereinafter also referred to as a gob) falls downward in the vertical direction.
  • the press units 120, 130, 140, and 150 are formed by sandwiching gobs at predetermined press positions in the air with a pair of press surfaces facing each other from both sides of the lump dropping path, thereby forming glass. Form a blank.
  • the four sets of press units 120, 130, 140, and 150 are provided every 90 degrees with the molten glass outlet 111 as the center.
  • the viscosity of the molten glass when it flows out from the molten glass outlet 111 is preferably in the range of 500 dPa ⁇ s to 1050 dPa ⁇ s.
  • Each of the press units 120, 130, 140, and 150 is driven by a moving mechanism (not shown) and can advance and retreat with respect to the molten glass outlet 111. That is, a catch position (a position where the press unit 140 is drawn with a solid line in FIG. 4) located directly below the molten glass outlet 111 and a retreat position (the press unit 120 in FIG. 4) away from the molten glass outlet 111.
  • a catch position a position where the press unit 140 is drawn with a solid line in FIG. 4 located directly below the molten glass outlet 111
  • a retreat position the press unit 120 in FIG. 4
  • the cutting unit 160 is provided on the path of the molten glass between the catch position (gob capture position by the press unit) and the molten glass outlet 111.
  • the cutting unit 160 cuts out the molten glass flowing out from the molten glass outlet 111 to an appropriate amount to form a gob.
  • the cutting unit 160 has a pair of cutting blades (an upper cutting blade 161 and a lower cutting blade 162) that are arranged so as to be shifted from each other in the vertical direction and are opposed to each other in the horizontal direction.
  • the cutting blades 161 and 162 cooperate to cut the molten glass. Specifically, the cutting blades 161 and 162 are driven to intersect on the molten glass path at a fixed timing, and when the cutting blades 161 and 162 intersect, the molten glass is cut out to obtain gob. .
  • the cutting unit 160 is provided with a plurality of guide members 163 for guiding the gob G G cut out from the molten glass L G in the cutting step to catch position.
  • Each guide member 163 has a shape extending in the vertical direction, and is arranged below the cutting blades 161 and 162 at a predetermined interval around the molten glass outlet 111.
  • the surface facing the dropping path of the gob G G of the surface of the guide member 163 is formed in a planar shape along the vertical direction, so as to guide the gob G G in fall to catch position .
  • Each of the plurality of guide members 163 may be arranged so as to face the other of the guide member 163 via the dropping path of the gob G G.
  • the distance between the pair of guide members 163 opposite to it may be formed to the extent that the gob G G may fall to catch position while in contact with the guide member 163.
  • the guide member 163 may not provided in plural, for example, to form a single guide member 163 in the vertical direction to extend the tubular, and arranged to drop the gob G G through the through hole of the guide member 163 May be.
  • the gob G G falls down in a state where the cutting unit G1 is always positioned vertically above.
  • each of the guide members 163 is not particularly limited, since there are cases where contact with the gob G G in falling, it is preferred to have heat resistance. Further, each of the guide members 163, in order to prevent the gob G G in drop adheres, preferably wettability to glass is composed of a material having low.
  • each guide member 163 may be made of ceramic or the like, or may be made of a material whose surface is plated (for example, gold plating or platinum plating).
  • the press unit 120 includes a first die 121, a second die 122, a first drive unit 123, and a second drive unit 124.
  • the first die 121 is each of the second die 122 is a plate-like member having a surface for press-forming the gob G G.
  • the normal direction of the two surfaces is a substantially horizontal direction, and the two surfaces are arranged to face each other in parallel.
  • the first drive unit 123 moves the first mold 121 forward and backward with respect to the second mold 122.
  • the second drive unit 124 moves the second mold 122 forward and backward with respect to the first mold 121.
  • the first drive unit 123 and the second drive unit 124 have a mechanism for rapidly bringing the surface of the first mold 121 and the surface of the second mold 122 into close proximity.
  • the 1st drive part 123 and the 2nd drive part 124 are the mechanisms which combined the air cylinder, the solenoid, and the coil spring, for example. Note that the structure of the press units 130, 140, and 150 is the same as that of the press unit 120, and a description thereof will be omitted.
  • Each press unit After moving into the catch position, the drive and the second drive unit first driving unit, the gob G G to fall first type and of predetermined sandwiched in Question second type thickness And a circular glass blank G is produced.
  • the cutting portion G1 of the gob G G because they are partially dissipated by thermal conduction upon contact with a pair of cutting blades 161 and 162, the temperature is lower than the other portions of the surface of the gob G G State. For this reason, when the cutting part G1 comes into contact with the press surface of the mold during pressing, the periphery of the cutting part G1 cools and hardens faster than other parts, so that a shear mark is formed in a relatively deep place (for example, 50 ⁇ m) of the glass blank. Will occur. Therefore, each of the press unit, as part a pair of mold press surfaces except the cut portion G1 of the total surface of the gob G G is first contacted, it is preferred to press-mold the gob G G.
  • the press position of the pair of dies has only to be adjusted.
  • relatively high temperature of the molten glass inside the gob G G is, jump out outward reheated cut portion G1 of the gob G G.
  • the molten glass is stretched, it is cooled and solidified with a small temperature difference between the cut portion of the molten glass and other portions, so that the depth of the shear mark in the glass blank becomes shallow (thinner). For this reason, it becomes easy to remove the shear mark in a processing step such as a grinding step or a polishing step.
  • the first conveyor 171, the second conveyor 172, the third conveyor 173, and the fourth conveyor 174 are provided below the retreat positions of the press units 120, 130, 140, and 150, respectively.
  • Each of the first to fourth conveyors 171 to 174 receives the glass blank G falling from the corresponding press unit and conveys the glass blank G to the next process apparatus (not shown).
  • the press units 120, 130, 140, and 150 are sequentially moved to the catch position, and are moved to the retreat position with the gob interposed therebetween. For this reason, the glass blank G can be continuously formed without waiting for the cooling of the glass blank G in each press unit.
  • S1 in FIG. 6 is a side view before the cutting blades 161 and 162 of the molten glass L G and the cutting unit 160 is in contact.
  • S2 in FIG. 6 the cutting blades 161 and 162 of the cutting unit 160 is a side view of the cut molten glass L G.
  • S3 of FIG. 6 is a side view showing a state in which the gob G G drops.
  • S4 in FIG. 6 is a side view illustrating a state where the pressing unit 120 is press-molded gob G G.
  • the molten glass L G is continuously flowing out from the molten glass outflow port 111.
  • the upper cutting blade 161 and the lower cutting blade 162 by driving the upper cutting blade 161 and the lower cutting blade 162 at a predetermined timing, cutting the molten glass L G.
  • cut molten glass becomes gob G G.
  • the time for driving the cutting unit 160 for example, as a gob G G radius of about 10mm is formed, the outflow amount and the cutting unit 160 per unit time of the molten glass L G The driving interval is adjusted.
  • the shape of the gob G G of the cut point (the time it was disconnected from the molten glass L G) is a vertically asymmetrical shape with respect to the horizontal plane passing through the vertical center of the gob G G.
  • the ratio of the horizontal direction of the longest dimension and the vertical direction of the longest dimension in the horizontal projection plane, in the vertical projection plane of the gob G G of the time of the cut for example, 1: 1.5-3.
  • instability tends to occur in the fall when the shape of such a gob G G.
  • the weight of the gob G G is 7 ⁇ 15 g.
  • Made gob G G falls to the first die 121 of the pressing unit 120 toward the gap between the second die 122. At this time, by the gob G G falls while contacting the respective guide members 163, falling trajectory of the gob G G is stabilized. Then, at the timing when the gob G G enters the first die 121 in the gap of the second die 122, such that the first die 121 second die 122 approach each other, the first driving unit 125 and the second drive The unit 126 is driven. Thereby, as shown in S4 of FIG. 6, the gob GG is captured (caught) between the first mold 121 and the second mold 122.
  • the gob G G and the press surface 121a of each mold 121 and 122 since the fall trajectory of the gob G G is stabilized, the gob G G and the press surface 121a of each mold 121 and 122, the first contact region between 122a becomes constant. Furthermore, the press surface 121a of the first die 121 and the press surface 122a of the second die 122 are in close proximity at a predetermined interval, and the press surface 121a of the first die 121 and the second die 122 are in close proximity. gob G G sandwiched between the press surface 122a is formed into a thin plate.
  • the press surface 121a of the first die 121 and the press surface 122a of the second die 122 are maintained.
  • Each is provided with protruding spacers 121b and 122b. When the spacers 121b and 122b come into contact with each other, the distance between the press surface 121a of the first die 121 and the press surface 122a of the second die 122 is maintained constant, and a plate-like space is created.
  • the first mold 121 and the second mold 122 are provided with a temperature adjustment mechanism (not shown).
  • the temperature of the first die 121 and second die 122 is a temperature adjusting mechanism, it is preferably adjusted to a temperature lower than a strain point of the molten glass L G.
  • the gob G G is formed into a substantially circular shape spread within a very short period of time along the pressing surface 122a of the press surface 121a and the second die 122 of the first die 121, further it is cooled non Solidifies as crystalline glass. Thereby, the glass blank G is produced.
  • the glass blank G formed in this embodiment is, for example, a circular plate having a diameter of 75 to 80 mm and a thickness of about 1 mm, depending on the size of the target magnetic disk glass substrate.
  • the press unit 120 quickly moves to the retracted position. Subsequently, other press unit 130 is moved to the catch position by the pressing unit 130, press the gob G G is performed.
  • the first die 121 and the second die 122 are closed until the glass blank G is sufficiently cooled (for example, until the temperature becomes lower than the bending point). To maintain. Thereafter, the first driving unit 123 and the second driving unit 124 are driven to separate the first mold 121 and the second mold 122, and the glass blank G falls off the press unit 120 and is at the lower part. It is received by the conveyor 171 (see FIG. 4).
  • the first die 121 and the second die 122 are closed within an extremely short time of 0.1 seconds (about 0.06 seconds), and the press surface 121a of the first die 121 and the first die 121 are closed.
  • the molten glass comes into contact with the entire press surface 122a of the second mold 122 almost simultaneously. For this reason, it is suppressed that the press surface 121a of the 1st type
  • the gob G G is formed into a circular shape, the temperature distribution is substantially uniform in the glass blank G to be shaped It becomes. For this reason, when the molten glass is cooled, the distribution of the shrinkage amount of the glass material is small, and the distortion of the glass blank G hardly occurs. Therefore, the flatness of the main surface of the manufactured glass blank material G is improved as compared with a glass blank manufactured by conventional press molding, and the target flatness of the main surface necessary as a glass substrate for a magnetic disk is set. Can do.
  • the surface roughness of the press surface 121a and the press surface 122a is adjusted so that the arithmetic average roughness Ra of the glass blank G is 0.01 ⁇ m to 10 ⁇ m, preferably 0.01 ⁇ m to 1 ⁇ m. can do.
  • FIG. 7 is a diagram for explaining a modification of the embodiment shown in FIG.
  • the plurality of guide members 163 may be provided at intervals in the vertical direction. In this case, by the gob G G falls while contacting the respective guide members 163, it is possible to stabilize the falling trajectory of the gob G G.
  • the guide member 163 may be integrally provided on the lower surface of the upper cutting blade 161. In this case, the guide member 163 has a shape extending vertically downward, when the pair of cutting blades 161 and 162 intersect (i.e., when the gob G G was obtained by cleavage of the molten glass L G), It is formed so that the vertically lower end faces the catch position.
  • FIG. 7 is a diagram for explaining a modification of the embodiment shown in FIG.
  • the plurality of guide members 163 may be provided at intervals in the vertical direction. In this case, by the gob G G falls while contacting the respective guide members 163, it is possible to stabilize the falling trajectory of the gob G G.
  • step S20 Scribe process
  • the scribe means two concentric circles (an inner concentric circle and an outer concentric circle) by a scriber made of super steel alloy or diamond particles on the surface of the glass blank G in order to make the formed glass blank G into a ring shape of a predetermined size.
  • -Shaped cutting line linear scratch.
  • the glass blank G scribed in the shape of two concentric circles is partially heated, and due to the difference in thermal expansion of the glass blank G, the outer portion of the outer concentric circle and the inner portion of the inner concentric circle are removed. Thereby, an annular glass substrate is obtained.
  • An annular glass substrate can also be obtained by forming a circular hole in the glass blank G using a core drill or the like.
  • the shape processing step includes chamfering processing (chamfering processing of the outer peripheral end portion and the inner peripheral end portion) on the end portion of the glass substrate after the scribe step.
  • a chamfering process is a shape process which chamfers with a diamond grindstone in the outer peripheral end part and inner peripheral end part of the glass substrate after a scribe process.
  • the chamfer angle is, for example, 40 to 50 degrees with respect to the main surface.
  • step S40 Grinding process with fixed abrasive
  • grinding machining
  • a double-side grinding apparatus having a planetary gear mechanism.
  • the double-sided grinding apparatus has a pair of upper and lower surface plates (upper surface plate and lower surface plate), and a glass substrate is sandwiched between the upper surface plate and the lower surface plate. And by moving either the upper surface plate or the lower surface plate, or both, the glass substrate and each surface plate are moved relatively to grind both main surfaces of this glass substrate. Can do.
  • step S50 End face polishing process
  • the end face polishing of the glass substrate is performed in the end face polishing process.
  • mirror finishing is performed on the inner peripheral end surface and the outer peripheral end surface of the glass substrate by brush polishing.
  • a slurry containing fine particles such as cerium oxide as free abrasive grains is used.
  • step S60 First polishing (main surface polishing) step
  • polishing is given to the main surface of the glass substrate after an end surface grinding
  • the purpose of the first polishing is, for example, to remove scratches and distortions remaining on the main surface when grinding with fixed abrasive grains, or to adjust minute surface irregularities (microwaveness, roughness).
  • polishing is performed using a double-side polishing apparatus equipped with a planetary gear mechanism while applying a polishing liquid.
  • polishing unlike abrasive with fixed abrasive grains, free abrasive grains turbid in the slurry are used instead of fixed abrasive grains.
  • the double-side polishing apparatus has a pair of upper and lower surface plates (upper surface plate and lower surface plate), and a glass substrate is sandwiched between the upper surface plate and the lower surface plate.
  • an annular flat polishing pad is attached to the upper surface of the lower surface plate and the bottom surface of the upper surface plate as a whole. And, by moving either the upper surface plate or the lower surface plate, or both, the glass substrate and each surface plate are moved relatively to polish both main surfaces of the glass substrate. Can do.
  • step S70 Chemical strengthening process
  • the glass substrate after the first polishing step is chemically strengthened.
  • the chemical strengthening solution for example, a mixed solution of potassium nitrate (60% by weight) and sodium sulfate (40% by weight) can be used.
  • the chemical strengthening solution is heated to 300 ° C. to 400 ° C., for example, and the cleaned glass substrate is preheated to 200 ° C. to 300 ° C., for example, and then the glass substrate is placed in the chemical strengthening solution, for example, 3 hours to 4 hours. Immerse.
  • the immersion is preferably performed in a state of being accommodated in a holder so that the plurality of glass substrates are held by the end faces so that both main surfaces of the glass substrate are chemically strengthened.
  • the lithium ions and sodium ions on the surface layer of the glass substrate are respectively replaced with sodium ions and potassium ions having a relatively large ionic radius in the chemical strengthening solution.
  • a compressive stress layer is formed on the glass substrate and the glass substrate is strengthened. Note that the chemically strengthened glass substrate is cleaned. For example, after washing with sulfuric acid, it is washed with pure water or the like.
  • step S80 Second polishing (final polishing) step
  • polishing is given to the glass substrate after a chemical strengthening process.
  • the second polishing step aims at mirror polishing of the main surface.
  • the double-side polishing apparatus used in the first polishing process is used.
  • the difference from the first polishing step is that the type and particle size of the free abrasive grains are different and the hardness of the resin polisher is different.
  • the free abrasive grains used in the second polishing step for example, fine particles such as colloidal silica made turbid in the slurry are used.
  • the polished glass substrate is washed with a neutral detergent, pure water, IPA or the like to obtain a glass substrate for a magnetic disk.
  • a neutral detergent, pure water, IPA or the like it is preferable that the second polishing step is performed because the level of the surface irregularities on the main surface of the glass substrate can be further improved.
  • the roughness (Ra) of the main surface can be made 0.1 nm or less and the micro waveness (MW-Rq) of the main surface can be made 0.1 nm or less.
  • the pressing surfaces of the respective molds 121 and 122 at the pressing position between the cutting process and the pressing process. 121a, initial contact area between the gob G G at 122a is to be constant, and guides the fall of the gob G G.
  • the processing amount can be easily set in processing steps such as a grinding step and a polishing step, and the manufacturing efficiency of the magnetic disk glass substrate can be improved.
  • the shape of the gob G G of the time of the cut are the vertically asymmetrical shape with respect to the horizontal plane passing through the center of the gob G G, when the gob G G is rotated in the fall, each gold press surface 121a of the mold 121, the first point of contact between the gob G G within 122a occurs variation in time of the press.
  • the rotation of the gob G G is suppressed, possible to further improve the accuracy of the initial contact position between the gob G G in the press surface 121a, the 122a of each mold 121 and 122
  • the variation in temperature distribution in the press surface of the mold for each press becomes smaller, and the variation in the flatness in the solid surface of the glass blank and the flatness between individuals can be further reduced.
  • the following experiment was performed.
  • the gob diameter is 20 mm
  • the gob weight is 10 g
  • the drop of the gob is guided by a plurality of guide members 163 as shown in FIG. 7, 100 glass blanks are formed, and the die is pressed at the time of pressing.
  • the average deviation of the gob fall position from the center position of the surface was measured.
  • difference of a fall position the unevenness
  • the flatness of the molded glass blank was measured using a commercially available flatness tester, and the value of the variation in flatness was obtained.
  • the results are shown in Table 1 as Examples 1 to 3. In each of Examples 1 to 3, the interval between guide members adjacent in the vertical direction is different.
  • 100 glass blanks are molded, and the average value of the shift position of the gob from the center position of the press surface of the mold at the time of pressing 100 sheets and The variation width of the flatness of the molded glass blank was measured. The results are shown in Table 1 as Example 4.
  • the shear mark could be removed with a 30 ⁇ m margin on one side with 70 out of 100 glass blanks.
  • the shear mark could be removed with a margin of 100 ⁇ m (50 ⁇ m on one side) with 97 glass blanks out of 100 sheets.
  • the sheer marks could be removed with 100 ⁇ m margins in all the glass blanks out of 100 sheets.
  • FIG. S1 of FIG. 9 is a diagram showing a state before making a gob
  • S2 of FIG. 9 is a diagram showing a state in which the gob G G were made
  • S3 in FIG. 9, the gob G G drops is a diagram showing a state
  • S4 of FIG. 9 is a diagram showing a state where the glass blank G was made by press-forming the gob G G.
  • the size of the pressing force by the air, the rotation of the gob G G in the horizontal direction of movement or falling of the gob G G in fall may be a degree to be regulated.
  • the wind pressure is 0.5 MPa or more and 3 MPa or less
  • the air volume is 10 L / min to 100 L / min
  • the air temperature is room temperature or more.
  • Table 2 shows the average value of the drop position deviation and the flatness variation of the glass blank when the driving speed of the lower cutting blade 162 is changed with respect to the driving speed of the upper cutting blade 161.
  • Table 2 shows the average value of the drop position deviation when 100 glass blanks are molded in each example, and the shear mark removal rate when grinding 100 ⁇ m (one side 50 ⁇ m).
  • the cutting unit 160 as shown in FIG. 10, the molten glass L G to be cut in the cutting step, the path of the molten glass L G
  • a pair of pressing members (a first pressing member 163 and a second pressing member 164) are provided.
  • the pressing members 161 and 162 are provided in the vicinity of the lower side of the cutting blades 161 and 162 and are opposed to each other in the horizontal direction with the position directly below the molten glass outlet 111 as a center.
  • Each pressing member 163, 164 is driven by a moving mechanism (not shown), and can move forward and backward in the horizontal direction with respect to the center between the pressing members 163, 164 (that is, the position directly below the molten glass outlet 111). .
  • Each pressing member 163 and 164 when the molten glass L G is cut by the cutting blades 161 and 162 move toward the center between the respective pressing members 163 and 164, in a state in which communication with the molten glass outflow port 111 Add a pressing force toward the horizontal direction molten glass L G in contact.
  • the magnitude of this pressing force can be a degree of movement in the horizontal direction is restricted in the molten glass L G.
  • the pressing member 163 is moved in the direction away from each other. At this time, the gob falls toward the catch position.
  • the rotational moment based on being pressed from the cutting blade 161, 162 during cutting of the molten glass L G is less likely to occur in the gob (including a portion that is pressed from the pressing member 163 and 164). For this reason, the fall stability of the gob (that is, the stability of the rotation and the drop trajectory) is improved.
  • each holding member 163 is not particularly limited, it is necessary to press in contact with the molten glass L G, it is preferable to have a heat resistance which does not lose the heat of the molten glass L G.
  • Each pressing member 163 and 164 in order to prevent the gob from adhering when dropping the gob cut out from the molten glass L G, preferably wettability to glass is composed of a material having low.
  • each pressing member 163, 164 may be made of ceramic or the like, or may be made of a material whose surface is plated (for example, gold plating or platinum plating). Good.
  • the area of the portion contacting the molten glass L G of the pressing member 163 and 164, from the viewpoint of reducing the amount of heat of the molten glass L G discharged through the respective pressing members 163 and 164 are formed smaller It is preferable.
  • FIG. S1 of FIG. 11 is a side view before the cutting blades 161 and 162 of the molten glass L G and the cutting unit 160 is in contact.
  • the cutting blades 161 and 162 of the cutting unit 160 is a side view of the cut molten glass L G.
  • 11 is a side view when the pressing members 163 and 164 of the cutting unit 160 are moved away from each other.
  • S4 of FIG. 11 is a side view illustrating a state where the pressing unit 120 is press-molded mass G G of the molten glass.
  • the molten glass L G is continuously flowing out from the molten glass outflow port 111.
  • the pressing member 163 is moved in the horizontal direction as to approach each other to press the horizontal direction in contact with the molten glass L G.
  • it is restricted movement in the horizontal direction of the molten glass L G.
  • S2 of FIG. 11 by driving the upper cutting blade 161 and the lower cutting blade 162 at a predetermined timing, cutting the molten glass L G.
  • cut molten glass becomes gob G G.
  • each time for driving the cutting unit 160 for example, as a gob G G radius of about 10mm is formed, the outflow amount and the cutting unit 160 per unit time of the molten glass L G The driving interval is adjusted.
  • the shape of the gob G G of the cut point (the time it was disconnected from the molten glass L G) is a vertically asymmetrical shape with respect to the horizontal plane passing through the vertical center of the gob G G.
  • the ratio of the horizontal direction of the longest dimension in the vertical and the direction of the longest dimension, the vertical projection plane in the vertical horizontal projection plane of the gob G G of the time of the cut for example, 1: 1.5-3.
  • instability tends to occur in the fall when the shape of such a gob G G.
  • the weight of the gob G G is 7 ⁇ 15 g.
  • the gob G G made, as shown in S3 of FIG. 11, by the pressing member 163 is moved in the horizontal direction as to be spaced apart from each other, the first mold 121 of the press unit 120 and the It falls toward the gap between the two molds 122.
  • the first drive unit 125 and the second driving unit 126 are driven. Accordingly, as shown in S4 of FIG. 11, the gob GG is captured (caught) between the first mold 121 and the second mold 122.
  • the press surface 121a of the first mold 121 and the press surface 122a of the second mold 122 are in close proximity at a predetermined interval, and the press surface 121a of the first mold 121 and the second surface gob G G sandwiched between the press surface 122a of the mold 122 is shaped into a thin plate.
  • FIG. 12 is a diagram for explaining a modification of the embodiment shown in FIG.
  • the first pressing member 163 is provided integrally with the upper cutting blade 161
  • the second pressing member 164 is provided integrally with the lower cutting blade 162.
  • S1 in FIG. 12 is a diagram showing a state before making a gob, S2 in FIG. 12, gob G G in a state in which movement is restricted in the horizontal direction of the molten glass L G by the pressing member 163, 164 is a diagram showing a state in which were made, S3 in FIG.
  • FIG. 12 is a diagram showing a state in which the gob G G drops by cutting unit 160 is driven such that each pressing member 163 and 164 are separated
  • Figure S4 in 12 is a diagram showing a state where the glass blank G by press-forming the gob G G were made.
  • the molten glass L G is continuously flowing out from the molten glass outflow port 111.
  • the gob G G cut out from the molten glass L G is in a state of being held by the holding members 163, 164 provided in each cutting blade 161, 162.
  • the pressing members 163 and 164 move in the horizontal direction so as to be separated from each other, so that the gob GG has the first mold 121 and the second mold of the press unit 120. It falls toward the gap of the mold 122.
  • the gob G G as shown in S4 of FIG. 12, by the first mold 121 is sandwiched by press molding and a second mold 122, circular glass blank G is produced.
  • the cutting step of press-forming step so as to regulate the movement in the horizontal direction of the molten glass L G in a state in which a pressing force toward the horizontal direction is added to the molten glass L G in a state of communication with the glass outflow port 111 (supply section) (hold state), and cutting the molten glass L G.
  • the rotational moment based on being pressed from the cutting blade 161, 162 during cutting of the molten glass L G is less likely to occur in the gob G G. Therefore, drop stability of the gob G G (i.e., stability of rotation and falling trajectory) is improved.
  • the shape of the gob G G of the time of the cut are the vertically asymmetrical shape with respect to the horizontal plane passing through the center of the gob G G, when the gob G G is rotated in the fall, each gold press surface 121a of the mold 121, the first point of contact between the gob G G within 122a occurs variation in time of the press.
  • the rotation of the gob G G is suppressed, possible to further improve the accuracy of the initial contact position between the gob G G in the press surface 121a, the 122a of each mold 121 and 122
  • the variation in temperature distribution in the press surface of the mold for each press becomes smaller, and the variation in the flatness in the solid surface of the glass blank and the flatness between individuals can be further reduced.
  • the average deviation of the gob dropping position was 4 mm
  • the flatness variation of the glass blank was 10 ⁇ m.
  • the shear marks could be removed with an allowance of 100 ⁇ m (50 ⁇ m on one side) for all 100 sheets.
  • difference of the gob fall position was 25 mm
  • variation in the flatness of the glass blank was 50 micrometers.
  • this modification is different from the embodiment, in the cutting step, without using the pressing member 163, it lies in that is configured to regulate the movement in the horizontal direction of the molten glass L G. More specifically, as shown in S1 of FIG. 13, the contact surface 162a of the molten glass L G of the lower cutting blade 162 (the contact portion), as suppress the horizontal displacement of the molten glass, upper cutting It is configured to bend so as to protrude toward the direction away from the blade 161 and to have a thickness in the vertical direction.
  • FIG. S1 in FIG. 12 is a diagram showing a state before making a gob
  • S2 of FIG. 14 shows a state in which the gob G G was made in a state in which movement is restricted in the horizontal direction of the molten glass L G a diagram
  • S3 in FIG. 14 is a diagram showing a state in which the gob G G drops
  • S4 of FIG. 14 is a diagram showing a state where the glass blank G was made by press-forming the gob G G .
  • the cutting step in a state where the molten glass L G is pressed by the air flowing in horizontal direction, it lies in that is configured to cut the molten glass L G.
  • a plurality of blowers (not shown) are provided at predetermined intervals around the molten glass outlet 111 near the lower portions of the cutting blades 161 and 162.
  • the predetermined amount of air sent from the air blower flows in the horizontal direction toward the position right under the molten glass outflow port 111.
  • the molten glass L G is by receiving a predetermined pressing force by the air, is regulated movement in the horizontal direction of the molten glass L G.
  • the size of the pressing force by the air may be a degree of movement in the horizontal direction is restricted in the molten glass L G.
  • the glass outlet 111 in the cutting step of press-forming step, so as to regulate the movement in the horizontal direction of the molten glass L G, the glass outlet 111 a pressing force toward the horizontal direction (feed portion ) and while applying the molten glass L G of connected state, and cutting the molten glass L G.
  • the rotational moment based on being pressed from the cutting blade 161, 162 during cutting of the molten glass L G is less likely to occur in the gob G G. Therefore, drop stability of the gob G G (i.e., stability of rotation and falling trajectory) is improved.
  • the manufacturing method of the glass blank for magnetic discs and the manufacturing method of the glass substrate for magnetic discs of this invention are not limited to the said embodiment, and do not deviate from the main point of this invention. Of course, various improvements and changes may be made in the range.
  • the present invention is not limited to this example, and the present invention is not limited to this configuration as long as the gob is dropped and pressed.
  • the invention can be applied.
  • the present invention can be applied to a configuration in which a gob is received by one mold and then pressed.

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)

Abstract

L'invention concerne un procédé de fabrication d'une ébauche de verre pour disque magnétique avec une planéité exceptionnelle, dans le but de fabriquer efficacement un substrat de verre pour disque magnétique dans lequel des irrégularités de surface dans des surfaces primaires sont supprimées. La présente invention concerne un procédé de fabrication d'une ébauche de verre pour disque magnétique avec une paire de surfaces primaires, comprenant les éléments suivants : une étape de coupe dans laquelle du verre fondu est introduit à partir d'une unité d'alimentation de verre fondu et est coupé par l'action coordonnée d'une paire de lames de coupe disposées de façon à ce qu'elles s'opposent mutuellement l'une l'autre, et une masse de verre fondu provenant de cette coupe est amenée à chuter ; et une étape de pressage dans laquelle après l'étape de coupe, la masse de verre fondu est moulée par pressage par une paire de surfaces de moule de pressage dans une position de pressage prescrite pour former une ébauche de verre. Pendant la période de l'étape de coupe à l'étape de pressage, la chute de la masse de verre fondu est guidée de telle sorte que la région de contact initiale de la masse avec la surface de moule de pressage à la position de pressage soit constante.
PCT/JP2013/059505 2012-03-30 2013-03-29 Procédé de fabrication d'une ébauche de verre pour disque magnétique et procédé de fabrication d'un substrat de verre pour disque magnétique WO2013147149A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015163578A (ja) * 2014-01-31 2015-09-10 Hoya株式会社 磁気ディスク用ガラスブランクの製造方法、磁気ディスク用ガラス基板の製造方法、及び切断刃部材

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005263574A (ja) * 2004-03-19 2005-09-29 Konica Minolta Opto Inc 情報記録媒体用ガラス基板の製造方法
WO2011122303A1 (fr) * 2010-03-31 2011-10-06 Hoya株式会社 Procédé pour produire une ébauche de verre, procédé pour produire un substrat de support d'enregistrement magnétique, et procédé pour produire un support d'enregistrement magnétique

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005263574A (ja) * 2004-03-19 2005-09-29 Konica Minolta Opto Inc 情報記録媒体用ガラス基板の製造方法
WO2011122303A1 (fr) * 2010-03-31 2011-10-06 Hoya株式会社 Procédé pour produire une ébauche de verre, procédé pour produire un substrat de support d'enregistrement magnétique, et procédé pour produire un support d'enregistrement magnétique

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015163578A (ja) * 2014-01-31 2015-09-10 Hoya株式会社 磁気ディスク用ガラスブランクの製造方法、磁気ディスク用ガラス基板の製造方法、及び切断刃部材

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